Since a photographic light-sensitive material is generally composed of a support having an electric insulating property and photographic layers, electrostatic charges are frequently accumulated by contact friction between or separation from the surfaces of the same or dissimilar materials during the production or use of the photographic light-sensitive material. The electrostatic charges thus accumulated cause various problems. The most serious trouble is that accumulated static charge may discharge before development of the photographic light-sensitive material to cause lightening-like exposure of a light-sensitive emulsion layer, whereby in the development of the photographic film, spot-like, twig-like, or feather-like marks form. These marks are so-called static marks, and occurrence of the static marks greatly reduces the commercial value of the photographic film, or in some cases may result in complete loss of commercial value. For example, in the case of medical or industrial X-ray films, it is easily understood that the static marks may result in a very dangerous judgement or misdiagnosis. This phenomenon is a very troublesome problem, because it becomes clear for the first time by carrying out development. Further, these accumulated static charges cause secondary problems such as adhesion of dust to the surface of films, uneven coating, etc.
Static charges frequently accumulate during the production and use of photographic light-sensitive materials as described above. For example, such charges may be produced by contact friction of a photographic film against rollers during the production of the photographic film, or by separation of the surface of the emulsion layer from the surface of the support during winding or rewinding of the photographic film. Static charges are also produced in a finished photographic film by separation of the emulsion layer surface from the base surface in the case of performing winding or rewinding of a photographic film or in X-ray films by contact, separation, etc., between the X-ray films and mechanical parts or fluorescent intensifying screens in an automatic camera for X-ray films. In addition, they are generated by contact with packing materials, etc.
The occurrence of static marks of photographic light-sensitive materials induced by the accumulation of such static charges becomes more severe as the sensitivity of photographic light-sensitive materials increases and as the processing speed for photographic light-sensitive materials increases. In particular, since the sensitivity of photographic light-sensitive materials has become higher, and there is an increased likelihood that the photographic light-sensitive materials will be treated under severe conditions, such as high-speed coating, high-speed photographing, high-speed automatic development processing, etc., static marks have become increasingly likely to form.
In order to prevent these troubles caused by static charges, it is suitable to add antistatic agents to the photographic light-sensitive materials as described, for example, in U.S. Pat. Nos. 3,850,642, 3,754,924, 3,658,573 and 3,850,640. However, antistatic agents used conventionally in other fields cannot be used freely for photographic light-sensitive materials, because they are subjected to various specific restrictions due to the nature of the photographic light-sensitive materials. Namely, it is required for the antistatic agents capable of use in the photographic light-sensitive materials that not only is the antistatic ability excellent, but also that they do not have adverse influences upon photographic properties of the photographic light-sensitive materials, such as sensitivity, fog, granularity, sharpness, etc., that they do not have an adverse influence upon film strength of the photographic light-sensitive materials (namely, that the photographic light-sensitive materials are not easily injured by friction or scratching), that they do not have an adverse influence upon adhesion resistance (namely, that the photographic light-sensitive materials do not easily adhere when the surfaces of them are brought into contact with each other or with surfaces of other materials), that they do not accelerate deterioration of processing solutions for the photographic light-sensitive materials, and that they do not deteriorate adhesive strength between layers composing the photographic light-sensitive materials, etc. Accordingly, applications of antistatic agents to photographic light-sensitive materials are subject to many restrictions.
One method for overcoming problems caused by static charges comprises increasing electric conductivity of the surface of the photographic light-sensitive material so that static charges disappear within a short time, prior to spark discharging of the accumulated charges, as desribed in the aforementioned U.S. Patents.
Accordingly, processes for improving the electrically conductive property of the base or the surface of various coating layers in the photographic light-sensitive materials have been proposed hitherto. Of these processes, methods of using a surface active agent are utilized and many patents relating thereto are also known since these methods are effective and economical. For example, those described in U.S. Pat. Nos. 2,982,651, 3,454,652, 3,655,387, 3,850,640 and 3,850,641, British Pat. Nos. 1,399,488 and 1,496,534, etc., are known.
However, many of these substances exhibit great specificity, depending upon the kind of film base or the photographic composition, and there are cases that, although they produce a good result on certain specific film bases, photographic emulsions or other photographic elements, they are not only useless for preventing generation of static charges in case of using different film bases and photographic elements, but also have an adverse influence upon photographic properties thereof.
Particularly, static prevention for hydrophilic colloid layers is very difficult, and it frequently happens that the reduction in surface resistance is insufficient in low humidity conditions, and adhesion troubles occur in a photographic light-sensitive material itself or between a photographic light-sensitive material and other dissimilar matters at high temperature and high humidity conditions. Particularly, in light-sensitive materials in which both sides of the base are coated with photographic emulsions, such as medical direct X-ray light-sensitive materials, it has been difficult to develop techniques for effectively providing an antistatic property without having an adverse influence upon photographic properties. Thus, the application of antistatic agents to the photographic light-sensitive materials is very difficult, and their use is often limited to a certain range.
That is, there are many cases wherein, although they have excellent antistatic effects, they cannot be used for photographic light-sensitive materials since they exhibit adverse influences on the photographic properties of silver halide photographic emulsions, such as sensitivity, fog, granularity, sharpness, etc., or they form scum in a fix solution. For example, it is generally known that polyethylene oxide type compounds as described in U.S. Pat. No. 3,850,641 and cationic type compounds as described in U.S. Pat. No. 3,850,640 have a static prevention effect, but they frequently exhibit adverse influences on the photographic properties of silver halide emulsions, such as increasing fog, desensitization, reduction in granularity, etc.
It is also known that betaine type compounds as described in British Pat. No. 1,339,488 have a static prevention effect and they do not exhibit adverse influences on the photographic properties. However, when they are employed in photographic light-sensitive materials containing an anionic type surface active agent, scum is generated during development processing using an automatic developing machine (hereinafter referred to simply as "auto-developing machine"), water-insoluble substance is deposited on transporting rollers of the auto-developing machine (hereinafter referred to simply as "roller stain") and the water-insoluble substance adheres on the surfaces of films (hereinafter referred to simply as "film stain"). Therefore, these compounds have a disadvantage in that the commercial value of the photographic light-sensitive materials is greatly reduced.